Using a pan-neuronal GFP marker, we screened mutants with severely disorganized ventral nerve cords. We have identified and characterized 21 mutations. 15 mutations were alleles of four previously identified genes, and 6 mutations were alleles of three new genes that we named ven(ventral nerve cord abnormal). In
ven-1mutants, the ventral nerve cord was defasciculated and misrouted on the lateral body, and was sometimes detached from the body wall and floating free. Similar defects were sometimes observed in the dorsal cord. The Ven phenotype was observed in embryos, and mutant worms not exhibiting the Ven phenotype in L1 larvae remained normal at later stages. This indicates that the
ven-1gene is required during the embryonic or early larval development.
ven-1mutants also had defects in the body wall muscle (Mua/Mup), in the excretory cell (Exc) and in the hypodermal cells. Thus, all tissues affected in
ven-1mutants are in contact with both the basal lamina and the hypodermis.
ven-1was mapped on LGV between
sma-1and unc-76. We cloned
ven-1and found that
ven-1encodes a protein of 86 amino acid residues with a signal peptide. VEN-1 bears no homology to other proteins reported previously. Forced expression of the
ven-1gene either in neurons, in the muscles or in the hypodermis could rescue both the Ven and the Mua/Mup phenotypes in
ven-1mutants. Together with the phenotypes of
ven-1mutants, these results suggest that VEN-1 is secreted and may act in the basal lamina and/or on the hypodermis